There are many types of foam products to protect, or make more comfortable, areas of the body of a person. For example, a foam layer in a helmet protects one's head and a foam insole is used to provide comfort for the feet of the user. For some products, however, it is important and required that at least a portion of the insole be rigid, or at least semi-rigid, rather than the completely padded condition created by a product made entirely of foam. For example, a knee pad best protects the knee by having a rigid portion and yet should be rendered comfortable by having a foam portion positioned next to the knee of the user. Or the user of an insole may have feet which require that the arch or the heel be rigid with the rest of the insole being of the soft and pliant foam.
In the past, the formation of such a product required either insert molding the rigid item to the foam or the molding of two separate pieces which were then somehow, as by gluing, affixed to each other. That is, a rigid plastic material, for example, would be injection molded and then post applied to a molded foam article. However, not only does such a system require the molding of two separate parts, but also it requires the additional labor-intensive step of gluing and otherwise affixing the two components. Moreover, such glued components may well have a tendency to separate, dependent, for example, on the activity of the user. In addition, if it is desired to vary the thickness of the foam material or the thickness of the rigid material, multiple parts will have to be molded in multiple mold cavities.
Another tedious lamination process is shown in U.S. Pat. No. 5,994,225. There, an upper resilient foam layer and a lower mat are shaped for incorporation into footwear. The mat includes a stiff portion and a plurality of upper fibers which penetrate the foam material to attach the two layers. As with the other prior devices, such requires the separate formation of two pieces and the extra step of attaching the same, and, in addition, does not provide for partial or specially shaped stiffening of an otherwise resilient material.
The need exists, therefore, for a method of making a composite foam and rigid material product.